VIXEN New Ultra Fast Astrograph VSD 100/f3.8

$6,299.00

Ultra Fast Refractor designed for the Astrophotographer featuring
a 5 Elements in 5 Group Lens design.
This f/3.8 OTA is Optimized for Digital Imaging

The innovative wide and flat imaging field, that covers 645
medium format cameras, and e 5 elements in 5 group lens design
completely eliminates a violet tint in chromatic aberration
(blue halo). With an SD lens in the front objective group and
an ED lens in the rear objective group, this scope achieves
superb color correction. The blue halos around stars, that are
visible in astrophotography and are hard to reduce with a 4
elements in 4 group lens design, are corrected successfully.
In addition, astigmatism and coma aberrations are corrected
to an extremely high level of image quality.

The Strehl intensity on the lens design of the VSD100F3.8 is
better than that on a 4 elements in 4 group lens design by approximately
10%. It does not decrease abruptly on stars away from the center
of a photographic field. It is ideally suited to detect faint
stars. The image circle is as large as 70mm in diameter (60%
illuminated). The star images are as small as @ 15 microns around
the corners, resulting in excellent field flatness.

The lenses of the VSD100F3.8 have the most up-to-date coatings
of extremely high reflectivity. These have been developed to
match the characteristics of each lens element in order to avoid
the deterioration of image contrast due to the increase of lens
elements. It boasts of a 99.9% light transmission at the maximum
per lens surface and achieves superb images with extremely high
contrast with no ghost and no flare images. (Patent pending)

Precision
Glass Annealing Process and a Premium Zygo Verifier ATZ Laser Interferometer.
In the process of manufacturing optical glass, all the five lens
elements are annealed with a precision annealing process (The annealing
can straighten molecular arrangements of lens elements and thus
unify the characteristic of optical glass.) The homogeneity of refractivity
in optical glass is enhanced to the highest degree.

Spot Diagram

Center of frameEdge of full frame 35mmEdge of a digital 645 format Edge of full frame 645 format

4 elements in 4 group F3.8 optics (designed for reference)

Describing Lens Performance with MTF CharacteristicsVixen’s goal was to develop a process to outperform the
views from a premium photo lens. The result is the introduction
of MTF (Abbreviation of Modulation Transfer Function), previously
used for evaluating the optical performance of camera lenses.
The diagram clearly describes the optical performance of the VSD100F3.8
as compared to a 4 element 4 group design.Thus, it allows for
a more precise evaluation of the photographic performance as compared
to conventional spot diagrams. This is a new direction in the
choice of an astrograph.

The VSD100F3.8 has an oversized focuser that can be attached
to the 645 medium format cameras without difficulty. Highly accurate
focusing is possible with the non-rotational helical fine focuser,
where the distance of drawing in and out the focuser can be read
as small as 20 microns with the provided vernier scale. All the
graduations are engraved.

Optional Focal Reducer and Optional Tele-Extender

A focal reducer (0.79x) with the optical design of 3 elements
in 3 groups and a tele-extender (1.58x) with the optical design
of 4 elements in 3 groups will be available as optional parts.
With the use of these optional accessories, the VSD100F3.8 can
be transformed to an even faster astrograph with 300mm in focal
length at F3.0, or can be converted to a more multi use optical
tube with 600mm in focal length at F6.0 for observing planets
and other celestial objects.